Photoconductor drum locator



Filed Jan. -15, 1968- FIG. 1

Jan.20,1970 J. V. cm, JRQE A1 3,490,841

PHOTOCONDUCTOR DRUM LOCATOR 2 Sheets-Sheet 1 FIG. 3

INVENTORS.

JAMES' V. CELXJR ROBERT T. RITCHIE ATTORNEY.

Jan. 20, 1970 v, my, R; ET AL 3,490,841

.7 PHOTOCONDUCTOR DRUI LOCATOR Filed Jan. 15, 1958 2 Sheets-Sheet 2 FIG.2

United States Patent O 3,490,841 PHOTOCONDUCTOR DRUM LOCATOR James V.Cely, Jr., and Robert T. Ritchie, Lexington,

Ky., assignors to International Business Machines Corporation, Armonk,N.Y., a corporation of New York Filed Jan. 15, 1968, Ser. No. 697,719Int. Cl. G03g 15/00 US. Cl. 355-3 7 Claims ABSTRACT OF THE DISCLOSURE Aphotocopying drum apparatus which is detachably mounted for rotation onthe outer section of a shaft having two sections which are connected bya universal joint. One end of the drum is supported by a sleeve. Theother end of the drum is supported by a chuck having three circularsegments which can be pivoted about a horizontal axis perpendicular tothe rotational axis of the drum. The drum is removed by pivoting theouter ends of the circular segments to the side and down so that thedrum can be removed over the chuck.

The inner section of the cantilevered shaft on a pivot arm. A forceprovided by a spring attached to the pivot arm, acts through thecantilevered shaft to the universal joint to cause the drum to pivotabout the universal joint until the outer surface of the drum is urgedinto contact with a plurality of positioning rollers. The points ofcontact of the rollers with the drum are located at a fixed distancefrom the image focusing lens of the photocopying apparatus so that theimage will remain focused on the surface of the drum to provide a sharp,clear image.

BACKGROUND OF THE INVENTION In the process for making copies ofdocuments by focusing a light image on a charged photoconductor to forma charged image corresponding to the document, which image is thendeveloped by exposing the charged image to an oppositely charged,pigmented developer composition, it is necessary to correctly positionthe photoconductor surface with respect to the optical system of theapparatus so that a sharply focused charged image is produced on thephotoconductor. A convenient way to accomplish such a photocopyingprocess is to use a revolving drum whose surface is covered with aphotoconductive material. Various stations are located around the drumfor charging the photoconductor, exposing the photoconductor to producethe charged image, developing the image on the photoconductor,transferring the image to the desired substrate, such as a sheet ofpaper, and cleaning the surface of the photoconductor for the nextcycle. While the photoconductor can be used a number of times which mayrun into the thousands, it nevertheless has a limited life and must beperiodically replaced because the developer tends to coat the surface ofthe photoconductor and adversely affect its photoconductive properties.The repeated charging and discharging of the photoconductor also causests photoconductive properties to gradually deteriorate.

Heretofore, expensive metal drums coated by special techniques withinorganic photoconductors have been used which drums are machined toclose tolerances so that the distance of the surface of the drum fromthe optical system can be closely controlled.

It has now been found that'relatively inexpensive photoconductor drumscan be employed using organic photoconductive materials which can beeasily coated on any substance, for example, cylinders of paper board,by conventional techniques. Therefore, when the photoconductor surfaceneeds replacement, the cylinder can be discarded and a fresh cylinderinserted in its place. Such cylinders cannot, of course, be made toclose tolerances nor do they have the ability of a rigid metal cylinderto retain their dimensional stability in service. Therefore, sharpcopies cannot be produced unless a means is devised to correctlyposition the image area of the cylinders with respect to the opticalsystem of the apparatus regardless of differing and constantly varyingsurface dimen- SlOIlS.

BRIEF DESCRIPTION OF THE INVENTION An apparatus has now been constructedwhich permits an inexpensive, disposable photoconductor drum to bedetachably mounted and accurately positioned in a copying apparatus.

In accordance with this invention, there is provided an apparatus formounting a photoconductor drum and accurately positioning the image areaof the drum which comprises a cantilevered shaft having two sectionswhich are joined endwise' by a connecting means which allows themovement of the axes of said sections relative to one another. Means areprovided to mount the drum on the outer section of the shaft.Positioning means are located adjacent to the image area of the drumwhich are adapted to contact the surface of the drum and keep the imagearea of the drum a fixed distance from the optical system of a'copyingapparatus so that the image to be reproduced will be sharply focused onthe photoconductor drum. A means is provided to apply a force to theshaft to cause the drum to pivot about the connecting means and thusmaintain the surface of the drum in contact with the positioning means.

DESCRIPTION OF THE DRAWINGS FIGURE 1 is a schematic representation of apreferred embodiment of the apparatus with parts broken away.

FIGURE 2 is a cross-sectional view of the apparatus of FIGURE 1 withparts broken away.

FIGURE 3 is a cross-sectional view of the apparatus of FIGURE 2 withparts broken away illustrating the releaseable chuck in the openposition.

DETAILED DESCRIPTION Referring now to FIGURE 1, drum 11, whose outersurface 12 is coated with a photoconductive material, is made of anyconvenient inexpensive material such as cardboard, thin metal sheet, orplastic. The image to be reproduced is focused on the image area(designated by dotted lines in FIGURE 1) by an optical system includingfocusing lens 13. Drum 11 is held in contact with rollers 19, which arelocated in pairs on shafts 21a and 2112, through the action of pivot arm23 mounted to pivot around fixed pivot 25 which is carried by pivotsupport 27 as is hereinafter described. Pivot arm 23 is urged in anupward direction by spring 29 mounted to frame 32. Each pair of rollers19 are mounted with carefully controlled concentricity at a fixeddistance from lens 13.

Turning now to FIGURE 2, drum 11 is mounted to rotate with cantileveredshaft 15 by chuck 39 and sleeve 22. Shaft 15 has two sections, innersection 17 and outer section 18 which are connected by a universal joint20. The inner end of section 17 of shaft 15 is mounted by bearings 73and 74 to sides 24 and 26 of pivot arm 23. Shaft 15 is driven by anyconvenient prime mover, for example, an electric motor, connected by apower train (not shown) to pulley 75 which is mounted on shaft 15 chuck47 by studs 49. Compression spring 51 is mounted coaxially with shaftwithin chuck 47. Spring 51 acts through collar 53 against the innersurfaces 55 of end portions 56 of circular segments 41 to urge segments41 to rotate in a counterclockwise direction around studs 49. Knob 57has an inner threaded portion 58 which is mounted to rotate on threadedportion 60 of section 18 of shaft 15. Knob 57 has a handle portion 62which when rotated will cause knob 57 to move to the left or right,depending upon the direction of rotation of handle 62, on shaft 15 bymeans of coacting threaded portions 58 and 60. Hollow sleeve portion 61of knob 57 has an end portion 63 which is adapted to contact outersurfaces 64 of end portions 56 of circular segments 41 and hold segments41 in a fixed position against the rotating force of spring 51.

Sleeve 22 is mounted to rotate with section 18 of shaft 15. The taperedsurface 65 of end 69 of sleeve 22 contacts the inner edge 70 of end 72of drum 11. Drum 11 is urged against surface 65 by circular segments 41whose tapered end portions 42 are urged into contact with the inner edge71 of end 75 of drum 11 by spring 51.

To remove drum 11, handle 62 of knob 57 is turned so as to cause it tomove to the left on shaft 15. This compresses spring 51 and causescircular segments 41 to be rotated in a clockwise direction around studs49. Ends 42 move outwardly and downwardly away from end 75 of drum 11until they are in the position illustrated in FIGURE 3. Drum 11 can thenbe removed to the right. To insert a new drum, the above process isreversed.

The image area of drum 11 is automatically located and maintained in thecorrect position with respect to lens 13 in the following manner as isillustrated in FIGURE 2. Pivot arm 23 is urged in an upward direction byan extension spring 29 which is mounted to hook 30 at one end and toframe 32 at the other so that pivot arm 23 pivots upwardly in aclockwise direction around fixed pivot 25 (FIGURE 1). This force actingthrough shaft 15, chuck 39 and sleeve 22 on drum 11 causes drum 11 topivot around universal joint until its outer surface 12 is in contactwith all four rollers 19. This contact is maintained during the rotationof drum 11 because drum 11 is continuously and automatically pivotedabout universal joint 20 by the action of pivot arm 23 which compensatesfor any variations in the dimensions of drum 11. The image area of drum11 is thereby always maintained a fixed distance from lens 13.

The invention permits the use of relatively inexpensive, disposablephotoconductor drums. The image area of the drum is automaticallypositioned during use to maintain the correct focusing relationshipbetween the optical system of the copying apparatus and thephotoconductor surface.

While the invention has been particularly shown and described withreference to a preferred embodiment thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention.

What is claimed is:

1. An apparatus for mounting a photoconductor drum and accuratelypositioning the image area of the drum with respect to the opticalsystem of a copying apparatus comprising:

a cantilevered shaft having inner and outer sections,

connecting means joining said section so as to allow movement of saidouter section relative to said inner section,

means for mounting said drum on said outer section of said shaft forrotation with said shaft,

positioning means located adjacent to the image area of said drum, saidmeans being adapted to contact the surface of said drum at a fixeddistance with respect to the optical system of said copying apparatus,and

means to apply a force to said cantilevered shaft to cause said drum tobe pivoted about said connecting means and urged into contact with saidpositioning means.

2. An apparatus for mounting a photoconductor drum and accuratelypositioning the image area of the drum with respect to the opticalsystem of a copying apparatus comprising:

a cantilevered shaft having inner and outer sections, a universal jointjoining said sections so as to allow movement of the axes of saidsections relative to one another,

means to drive said cantilevered shaft,

means for detachably mounting said drum on said outer section of saidshaft for rotation with said shaft,

positioning means located adjacent to the image area of said drum, saidmeans being adapted to contact the surface of said drum at a fixeddistance with respect to the optical system of said copying apparatus,and

means to apply a force to said cantilevered shaft to cause said drum topivot about said universal joint and be urged into contact with saidpositioning means.

3. An apparatus for mounting a photoconductor drum and accuratelypositioning the image area of the drum with respect to the opticalsystem of a copying apparatus comprising:

a cantilevered shaft having inner and outer sections,

a universal joint joining said sections so as to allow movement of theaxes of said sections relative one another,

means for mounting said drum for rotation with said outer section ofsaid shaft,

positioning means located adjacent to the image area of said drum saidmeans being adapted to contact the surface of said drum at a fixeddistance with respect to the optical system of said copying apparatus,and

means to apply a force to said cantilevered shaft to cause said drum topivot about said universal joint and be urged into contact with saidpositioning means.

4. The apparatus of claim 2 wherein said means for detachably mountingsaid drum comprises:

a sleeve mounted to rotate with said outer section of said shaft, saidsleeve having a tapered flange portion adapted to engage the inner edgeof one end of said drum,

a releasable chuck having a core mounted to rotate with said outersection of said shaft and a plurality of circular segments pivotallymounted to said core with the outer portions of said circular segmentsbeing adapted to contact the inner edge of the other end of said drumand urge said drum into contact with the tapered portion of said sleevesuch that said drum, sleeve and chuck rotate with said shaft,

and means for pivoting said circular segments outwardly and downwardlyaway from said inner edge of said drum to permit said drum to be removedover said chuck.

'5. The apparatus of claim 4 wherein said positioning means comprises apair of shafts located adjacent to the surface of said drum, said shaftsbeing substantially parallel to the axis of said drum, and a pair ofpositioning rollers concentrically mounted on each of said shafts suchthat the outer edges of said rollers contact the surface of said drumadjacent to the image area of said drum at a fixed distance from thefocusing lens of said copying machine.

6. The apparatus of claim 5 wherein said means to apply a force to saidcantilevered shaft comprises a pivot arm near one end of which the innerend of said cantilevered shaft is mounted for rotation, a fixed pivotmounting said pivot arm near its other end, and means to continuouslyurge the end of said pivot arm carrying said shaft to tend said arm torotate about said pivot in a direction to move said cantilevered shaftand drum toward said positioning means.

7. An apparatus for detachably mounting a photoconductor drum in acopying apparatus and accurately positioning the image area of the drumwith respect to the optical system of said copying apparatus comprising:

a cantilevered shaft having two sections said sections being connectedby a universal joint, the inner section of said shaft being mounted forrotation to one end of a pivot arm,

a fixed pivot for mounting said pivot arm at its other end,

means to drive said cantilevered shaft,

a releasable chuck mounted to rotate with said canti levered shaft onits outer section, said chuck being adapted to detachably engage theinner edge of one end of said drum,

a sleeve mounted on the outer section of said cantilevered shaft torotate with said shaft and located between said universal joint and saidchuck, one end of said sleeve having a flange portion adapted tofrictionally engage the inner edge of the other end of said drurn' suchthat said drum will rotate with said cantilevered shaft and pivot aboutsaid universal joint,

a pair of shafts located adjacent to the surface of said drum, saidshafts being substantially parallel to the axis of said drum,

a plurality of positioning rollers mounted on each of said shafts, theouter edges of said rollers being adapted to accurately locate the imagearea of said drum with respect to the optical system of said copyingmachine when the surface of said drum is brought into contact with saidrollers,

and means to apply a force through said pivot arm and said cantileveredshaft to cause said drum to be pivoted about said universal joint andurged into contact with said positioning rollers.

References Cited UNITED STATES PATENTS 2,832,311 4/1958 Byrne 355-32,975,758 3/1961 Bird 3553 3,420,151 1/1969 Levine 35516 JOHN M. HORAN,Primary Examiner LEO H. MCCORMICK, Assistant Examiner

